Paprosky Classification of Bone Loss in Acetabulum

Paprosky et al developed a classification scheme for acetabular bone loss.

Parameters:

(1) medial wall (teardrop)

(2) superior dome (hip center)

(3) anterior line (Kohler line)

(4) posterior column (ischium)

(5) bone loss

Parameter	Type 1	Type 2A	Type 2B
medial wall	intact	intact	intact
superior dome	no migration	mild migration, < 2 cm superomedial	moderate migration, < 2 cm superolateral
anterior line	intact	intact	intact
posterior column	intact	intact	intact
bone loss	mild	moderate	moderate

Parameter	Type 2C	Type 3A	Type 3B
medial wall	moderate lysis	moderate lysis	severe lysis
superior dome	mild migration, < 2 cm medial	severe migration, >= 2 cm superolateral	severe migration, >= 2 cm superomedial
anterior line	disrupted	intact	disrupted
posterior column	intact	moderate lysis	severe lysis
bone loss	moderate	severe, 10 to 2 o'clock	severe, 9 to 5 o'clock

where:

• Mild bone loss had > 50% cancellous remaining bone bed. Moderate bone loss had < 50% cancellous remaining bed.

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